Question:
I'd like to build a deck attached to my house that'll also be a
single-car carport (that is, the roof of the carport is a deck). Ideally
there will be posts on the left of the carport, but not on the right,
making much easier to pull in and out of the carport (and avoiding the
risk of the car hitting a post supporting the deck). It would be
acceptable to only have one post on the right side
The total width of the deck will probably be about one and half car
widths, maybe about 10 feet.
Is cantilevering the deck as described above possible? Or, maybe instead
of saying possible, is it a reasonable thing to try to do? How about
supporting the post-free corners of the deck with wires from above?
My guess is that doing it with a cantilever will probably be both
impractical and/or too expensive.
Any thoughts?
Answer:
I cantilevered a deck off of an add-on bedroom some 25 years ago. The trick,
in that case, was to run the joists well under the new addition. i.e. for a
ten foot deck, I used 16 foot joists and ran them six feet under, and
attached to, the joists that supported the new room. That option may or may
not be available to you.
I also had to put 45 degree angle joists on the back side. So, my pure
"clearance" was about 6 feet. Even with all of that, I had a "bouncy"
feeling when we were on the deck. We loved it and the appearance that it
gave. If I had to do it over, I'd find an engineer who could give me the
correct lengths, heights and sizes and quantities of 2 x 8's or whatever to
do it right.
Can it be done YES ( I did it). Should it be done by an amateur ( me )
without any real understanding of the loads? PROBABLY NOT. Get some
professional advice and have at it. It might be to your advantage to do the
cantilevered portion with steel or steel reinforcing the extended joists.
One thing you might want to do consider steel beams. My dad spec'ed steel
beams to clear span over an extra wide garage. It was rock solid upstairs,
I never thought about this much until I walked across a shorter span and
felt the bounce. My dad said the cost for the steel beams was close to
wood, but the installation was a little trickier.
